A double-kingpin skateboard truck, for example, as disclosed in U.S. Pat. No. 7,150,460, is distinguished from a single-kingpin skateboard truck by the double-kingpin truck's particular incorporation of a truck insert, which is attached between the axle and the base plate of a single-kingpin skateboard truck. More particularly, a known double-kingpin truck, as shown in FIG. 15, comprises a skateboard truck insert, as shown in FIG. 16, capable of being positioned between a base plate and an axle of a skateboard truck. The truck insert generally comprises an intermediary member; a truck insert pivot pin projecting from the intermediary member for positioning in a pivot pin receiving hole in the base plate; a mounting portion at a first end of the intermediary member with an oversized through hole; a blind hole at an end of the intermediary member opposite the first end for receiving a pivot pin projecting from the axle, and an axle bolt hole for receiving a 2 to 3 inch axle bolt extending from the axle, where the axle bolt hole is spaced from the blind hole and is located in the intermediary member between the mounting portion and the blind hole.
The inclusion of the extra 2 to 3 inch truck insert bolt, two bushings, insert pivot pin, and other components required for the truck insert component provides the double-kingpin skateboard truck a hyper-turning and hyper-traction ability, in comparison to a typical single-kingpin skateboard truck. The double-kingpin truck geometry is, therefore, well-suited for skateboard carving, pumping, slalom riding, and sidewalk surfing purposes. However, the same extra truck components required by the inclusion of the truck insert also cause the double-kingpin skateboard truck to have a much taller truck height profile, and also to be much more flexible than a single-kingpin skateboard truck, making the setup much less suitable for high-speed skateboard riding purposes. To address the truck height and speed stability problems inherent in such double-kingpin trucks, it is of great utility and benefit to lower the overall height profile of the skateboard truck as low as mechanically possible so as to reduce the overall center of gravity of the entire skateboard.
In U.S. Patent Publication 2005/0051983 a double-kingpin truck, as shown in FIG. 17, is disclosed. The truck comprises a second kingpin 200 with pivot end 199 that may be inserted into a face 208 of a base plate 207. However, one major deficiency associated with this prior art truck is that the intermediary member 201 in the truck has no mechanism disclosed for rotational restraint, or fixed alignment, of the second kingpin bolt 200 within the intermediary member 201 of the skateboard truck mechanism 400. Lacking such directional alignment and rotational restraint of the second kingpin 200 within the prior art intermediary member 201, predictable turning and directional control of the skateboard onto which the truck is installed is either not possible or severely inhibited. Without having a means of directional alignment, the leverage exerted on the intermediary member 201 from the combined compressional forces of the skate wheels 224 and the tilt of the deck from the skateboard rider's weight while riding, would force the mounting portion 202 of the truck to swing laterally back and forth relative to the bolt 203. This lateral pivoting and rotation of the mounting portion 202 around the bolt 203 can result in unwanted metal to metal contact between the mounting portion 202 with the bolt 203, which is rigidly fixed into the base plate 207 and passes through the middle of the mounting portion 202 of the intermediary member 201. Because of such unwanted, unpredictable, and uncontrollable rotation of the mounting portion, there is a high likelihood that after frequent contact with said bolt 203, the structural integrity of the aluminum mounting portion 202 would eventually fail and break. Because of this highly predictable mechanical hazard this particular prior art truck design is not suitable for safe skateboarding purposes, and a means of addressing this obvious deficiency is a primary goal of the present invention.
Thus, there is a need in the art for a double-kingpin skateboard truck incorporating a novel keyway slot and an L-shaped keyway bolt that safely integrates the double-kingpin modification while allowing for height-adjustability and improved high-speed performance characteristics.